When an adhesive film for decoration according to the prior art is bonded to a substrate article, air is entrapped between the adhesive and the substrate article, and to prevent entrapment, a considerably high level of skill is necessary. Further, a great deal of labor and time are necessary for the bonding work. When the conventional adhesive film for decoration is bonded to the substrate article and is used indoors and outdoors, the bonding strength rises with the passage of time, and it is extremely difficult to peel the adhesive film from the substrate article. Thus, a great deal of labor and time are also necessary.
An adhesive sheet material disclosed in Japanese Examined Patent Publication (Kokoku) No. 44-17040 and a positionable adhesive tape disclosed in Japanese Unexamined Patent Publication (Kokai) No. 3-181578 form recesses in a support or a carrier web, and dispose non-adhesive members or glass beads in the recesses. Because the adhesive does not directly come into contact with the substrate article, these tape and web have slidability and working becomes easier. However, the process step of forming the recesses in the support and the carrier web is necessary. After the film is pressed on the substrate article, the adhesive does not have protuberances any more, and the substrate article and the adhesive do not have point contact any more, either. Accordingly, when air remains on the substrate article at the center of the film, this air cannot be removed. Since surface contact is established when the film is press-bonded to the substrate article, the contact area increases with time and the bonding strength increases, so that re-peel is extremely difficult.
A pressure-sensitive adhesive composition disclosed in Japanese Examined Patent Publication (Kokoku) No. 45-17074 is obtained by mixing light-weight brittle glass beads having a thin wall with a liquid adhesive composition and coating and drying the mixture. The adhesive having protuberances obtained in this way has slidability because the adhesive does not come into direct contact with the substrate article, and working becomes easy. However, after the film is press-bonded on the substrate article, the glass beads are ruptured, and the substrate article and the adhesive do not have the point contact any more. Accordingly, if air remains at the center of the film, this air cannot be removed. Further, when the film is press-bonded to the substrate article, the contact area becomes greater with time and the bonding strength increases, so that re-peel is extremely difficult.
An adhesive tape for packaging disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 59-763 and an adhesive tape disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 59-37343 prevent entrapment of air by partial disposition of an adhesive layer. However, these tapes involve the problem in that because the adhesive must be scattered in a dot system or a stripe pattern, a specific coating machine for this purpose is necessary. Another problem is that the film surface gets uneven due to the dots or the stripe pattern which is partially disposed.
An air-permeable adhesive member disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2-45582 has a structure wherein an air-permeable adhesive layer containing hollow beads is disposed on a porous air-permeable substrate, and a large number of microspheres communicating with the pores in the substrate are disposed. According to this conventional art, the substrate is limited because it must be porous, and special equipment is necessary for partially removing an adhesive solution by a gas blow system or an air suction system from the air-permeable substrate side after the coating solution is applied. Another problem is that when an ink for decoration is applied, it closes the pores of the air-permeable substrate and initial performance cannot be obtained.
An outdoor adhesive sheet disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 59-54547 has a structure wherein a flat film is laminated on one of the surfaces of a film having a continuous foam layer formed thereon, and an adhesive layer is disposed on the other surface so that the gas generated from the substrate with time is allowed to permeate. However, this sheet is not free from the problem that air entrapped at the time of bonding cannot be removed because the adhesive layer is not air-permeable.
A re-peelable protective sheet disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 5-56938 has a structure wherein microspheric adhesive components are deposited with intervals between them on one of the surfaces of a support. This sheet involves the problem that the bonding strength to the bonded article is as low as 100 gf/25 and when it is used outdoors, it naturally peels.
A re-peelable adhesive sheet disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 61-168146 has a structure wherein an adhesive composition layer comprising elastic microspheres and an adhesive is formed on a substrate. A desired adhesive composition preparation solution is obtained by dispersing the microspheres and the adhesive in a volatile organic solvent. However, the elastic microspheres are obtained by a suspension polymerization method using water as a medium and in order to uniformly disperse them in the organic solvent, the water content must be removed. However, this process step has an extremely low level of productivity and another problem lies in that the elastic microspheres undergo deformation and degradation due to the influences of the organic solvent, and desired point contact cannot be obtained after the sheet is bonded to the bonded article. Still another problem is that the bonding strength cannot be controlled when the adhesive composition is applied to the entire surface of the substrate, and the adhesive must be coated in a pattern such as a square or a circle, so that a specific coating machine for this purpose is necessary.
A positionable adhesive having a high shearing force, which is disclosed in W092/13924, has a structure wherein an adhesive composition layer comprising elastic microspheres and an adhesive is formed on a substrate. Since a mixing ratio of the elastic microspheres to the adhesive is high, the elastic microspheres are packed in a high density to the adhesive layer, and since air passages necessary for deforming are not formed, air bubbles entrapped between the adhesive and the substrate article cannot be removed. Because such an adhesive film has a flat adhesive layer, bonding between the adhesive and the substrate article becomes bonding by surface contact, and because the bonding strength rises with the passage of time, re-peel is difficult.